.\"	$OpenBSD: mt.4,v 1.12 2013/06/02 20:42:27 tedu Exp $
.\"	$NetBSD: mt.4,v 1.3 1996/03/03 17:13:52 thorpej Exp $
.\"
.\" Copyright (c) 1980, 1991 Regents of the University of California.
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.\"     from: @(#)mt.4	6.4 (Berkeley) 3/27/91
.\"
.Dd $Mdocdate: June 2 2013 $
.Dt MT 4 vax
.Os
.Sh NAME
.Nm mt
.Nd
.Tn TM78 Ns / Tn TU-78
.Tn MASSBUS
magtape interface
.Sh SYNOPSIS
.Cd "mt* at mscpbus? drive?"
.Sh DESCRIPTION
The
.Tn TM78 Ns / Tn TU-78
combination provides a standard tape drive
interface as described in
.Xr mtio 4 .
Only 1600 and 6250
.Tn BPI
are supported; the
.Tn TU-78
runs at 125
.Tn IPS
and autoloads tapes.
.Sh DIAGNOSTICS
.Bl -diag
.It mu0: no write ring.
An attempt was made to write on the tape drive
when no write ring was present; this message is written on the terminal of
the user who tried to access the tape.
.It mu0: not online.
An attempt was made to access the tape while it
was offline; this message is written on the terminal of the user
who tried to access the tape.
.It "mu0: can't change density in mid-tape."
An attempt was made to write
on a tape at a different density than is already recorded on the tape.
This message is written on the terminal of the user who tried to switch
the density.
.It "mu0: hard error bnN mbsr=... er=X ds=...."
A tape error occurred
at block
.Em bn ;
the mt error register and drive status register are
printed in octal with the bits symbolically decoded.
Any error is fatal on non-raw tape; when possible the driver will have retried
the operation which failed several times before reporting the error.
.It mu0: blank tape.
An attempt was made to read a blank tape (a tape without even
end-of-file marks).
.It mu0: offline.
During an i/o operation the device was set offline.
If a non-raw tape was used in the access it is closed.
.El
.Sh SEE ALSO
.Xr mt 1 ,
.Xr intro 4 ,
.Xr mscpbus 4
.Sh HISTORY
The
.Nm
driver appeared in
.Bx 4.1 .
.Sh BUGS
If a physical error (non-data) occurs,
.Nm
may hang ungracefully.
.Pp
Because 800
.Tn BPI
tapes are not supported, the numbering of minor devices
is inconsistent with triple-density tape units.
Unit 0 is drive 0, 1600
.Tn BPI .
